1. Field of the Invention
An aspect of this disclosure relates to an information processing apparatus, an image generating method, and a storage medium.
2. Description of the Related Art
Apparatuses such as a multifunction peripheral including a copy function are used in our daily life or business to copy documents. With the advancement of copying technology, it has become difficult to distinguish between originals and copies. Also, when a document is repeatedly copied, it becomes difficult to determine the source or origin of the document.
For example, if a copy of a classified original document is circulated as the original, the security of the original document may be compromised. To prevent such a problem, it is necessary to guarantee (guarantee of originality) that a document is the original and not a copy. Also, to guarantee the security of documents, it is preferable to attach, to original documents, information regarding the original documents so that the sources or origins of copies and their distribution routes can be identified. To attach information to a document and thereby improve its security, it is preferable to process the document in such a manner that the processed results are normally not visible to human eyes.
Generally, carbon black having a light-absorption property is used as a black pigment for a black toner of an image forming apparatus. Here, Japanese Patent No. 4280460 discloses an image forming apparatus that uses a black toner having an infrared-reflection property. The image forming apparatus converts image data, which is obtained by scanning a document, into an electrostatic latent image, develops the electrostatic latent image using a developer including a black toner having an infrared-reflection property, and thereby forms an image having the infrared-reflection property on a recording medium such as paper. In Japanese Patent No. 4280460, a toner including a pigment that becomes white when reflecting infrared rays is used as the black toner having the infrared-reflection property.
Meanwhile, Japanese Laid-Open Patent Publication No. 2001-265181 discloses an image forming apparatus that forms an invisible image on a recording medium using a recording material that absorbs invisible light. More specifically, the image forming apparatus forms an invisible image on the recording medium under conditions that the difference in the maximum spectral reflectance in the visible light range between the recording medium and the recording material is less than or equal to 10% and the difference in the maximum spectral reflectance in the invisible light range between a visible image on the recording medium and the recording material is greater than or equal to 10%.
Further, Japanese Patent No. 2732342 and Japanese Patent No. 2732343 disclose technologies where an image is printed using an infrared-absorbing pigment over image information printed using an infrared-reflecting pigment to make the image information invisible to the naked eye. In the technology disclosed in Japanese Patent No. 2732342, an image is formed using a black ink made of an infrared-absorbing pigment over an image formed using a black ink made of an infrared-reflecting pigment. Similarly, in the technology disclosed in Japanese Patent No. 2732343, black toners made of two types of pigments are used.
According to the technology disclosed in Japanese Patent No. 4280460, an image is formed using a toner that reflects infrared rays when the image is copied. According to the technology disclosed in Japanese Laid-Open Patent Publication No. 2001-265181, an invisible image is formed on an original document using a toner that satisfies predetermined conditions. According to the technologies disclosed in Japanese Patent No. 2732342 and Japanese Patent No. 2732343, information printed on a card is hidden by forming an image over the information using a special toner.
Thus, in the related-art technologies described above, a special toner is used to add invisible information for distinguishing an original from a copy. With the related-art technologies, however, it is not possible to add invisible information to an original under circumstances where special toners are not usable.